From ede7791abf9cb8859d6d9aa23dc9540c6454b972 Mon Sep 17 00:00:00 2001
From: Vlad Voronenkov <v.v.voronenkov@ya.ru>
Date: Thu, 11 Aug 2022 16:35:39 +0200
Subject: [PATCH] Add TemperatureGradient quantity with related units.

---
 src/si/mod.rs                  |  1 +
 src/si/temperature_gradient.rs | 62 ++++++++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+)
 create mode 100644 src/si/temperature_gradient.rs

diff --git a/src/si/mod.rs b/src/si/mod.rs
index 90168a64..38cd5a04 100644
--- a/src/si/mod.rs
+++ b/src/si/mod.rs
@@ -113,6 +113,7 @@ system! {
         specific_heat_capacity::SpecificHeatCapacity,
         surface_electric_current_density::SurfaceElectricCurrentDensity,
         temperature_coefficient::TemperatureCoefficient,
+        temperature_gradient::TemperatureGradient,
         temperature_interval::TemperatureInterval,
         thermal_conductivity::ThermalConductivity,
         thermodynamic_temperature::ThermodynamicTemperature,
diff --git a/src/si/temperature_gradient.rs b/src/si/temperature_gradient.rs
new file mode 100644
index 00000000..f1e8233e
--- /dev/null
+++ b/src/si/temperature_gradient.rs
@@ -0,0 +1,62 @@
+//! Temperature gradient (base unit kelvin per meter, m⁻¹ · K).
+
+quantity! {
+    /// Temperature gradient (base unit kelvin per meter, m⁻¹ · K).
+    quantity: TemperatureGradient; "temperature gradient";
+    /// Dimension of temperature gradient, L⁻¹Th (base unit kelvin per meter, K · m⁻¹).
+    dimension: ISQ<
+        N1,     // length
+        Z0,     // mass
+        Z0,     // time
+        Z0,     // electric current
+        P1,     // thermodynamic temperature
+        Z0,     // amount of substance
+        Z0>;    // luminous intensity
+    units {
+        @kelvin_per_kilometer: prefix!(none) / prefix!(kilo); "K/km", "kelvin per kilometer",
+            "kelvins per kilometer";
+        @kelvin_per_hectometer: prefix!(none) / prefix!(hecto); "K/hm", "kelvin per hectometer",
+            "kelvins per hectometer";
+        @kelvin_per_meter: prefix!(none); "K/m", "kelvin per meter", "kelvins per meter";
+        @kelvin_per_centimeter: prefix!(none) / prefix!(centi); "K/cm", "kelvin per centimeter",
+            "kelvins per centimeter";
+        @kelvin_per_millimeter: prefix!(none) / prefix!(milli); "K/mm", "kelvin per millimeter",
+            "kelvins per millimeter";
+        @kelvin_per_micrometer: prefix!(none) / prefix!(micro); "K/µm", "kelvin per micrometer",
+            "kelvins per micrometer";
+    }
+}
+
+#[cfg(test)]
+mod test {
+    storage_types! {
+        use crate::num::One;
+        use crate::si::temperature_gradient as tg;
+        use crate::si::temperature_interval as ti;
+        use crate::si::quantities::*;
+        use crate::si::length as l;
+        use crate::tests::Test;
+
+        #[test]
+        fn check_dimension() {
+            let _: TemperatureGradient<V> = TemperatureInterval::new::<ti::kelvin>(V::one())
+                / Length::new::<l::meter>(V::one());
+        }
+
+        #[test]
+        fn check_units() {
+            test::<ti::kelvin, l::meter, tg::kelvin_per_meter>();
+            test::<ti::kelvin, l::centimeter, tg::kelvin_per_centimeter>();
+            test::<ti::kelvin, l::millimeter, tg::kelvin_per_millimeter>();
+            test::<ti::kelvin, l::micrometer, tg::kelvin_per_micrometer>();
+            test::<ti::kelvin, l::hectometer, tg::kelvin_per_hectometer>();
+            test::<ti::kelvin, l::kilometer, tg::kelvin_per_kilometer>();
+
+            fn test<TI: ti::Conversion<V>, L: l::Conversion<V>, TG: tg::Conversion<V>>() {
+                Test::assert_approx_eq(&TemperatureGradient::new::<TG>(V::one()),
+                    &(TemperatureInterval::new::<TI>(V::one())
+                        / Length::new::<L>(V::one())));
+            }
+        }
+    }
+}